Gimme a Break from the FAKE

Why do people insist on being fake? I know it sounds contradicting come from someone who is pledging a fraternity and who has changed the way he dresses because he's pledging. Honestly, I have gotten over the scene/indie phase and have realized that it's time to move on and to dress more professionally. Now, I LIKE wearing polos and clean-cut shorts and pants rather than band t-shirts and rugged shorts. Not that there's anything wrong with the way I dressed; I just feel that if I were to somehow arrive in a situation in which I am talking to a future employer or sponsor for some sort of scholarship, then I would be WAY more professional-looking with the way I dress now rather than with band t-shirts. 

ANYWAY, apart from that tangent on the way I dressed, why do people just act "cool" to fit in? Why do people blow off their real friends so they can hang out with their cool "friends". In contrast from the way I dress, I stick by my old friends while making new ones. I don't ditch anyone unless I HAVE to when it comes to school and church and other obligations. I have missed more social events at my fraternity than I might have wanted, but I did it in order to go home and hang out with my old friends and my girlfriend. But I know some people who completely change their personalities in order to fit in. I don't resent them because they don't hang out with me anymore, for we still hang out, but I resent them for thinking they are even more arrogant than they were before and put others down in order to feel cool. I know people who go to a party or something and HAVE to tell me EVERY SINGLE THING that happened there because they feel cool they experienced it. Funny thing is I WAS THERE TOO so I already know exactly what they're talking about. But they insist on explaining every detail to me anyway. Hmmmmmmmm.....I hate Miley Cyrus and Justin Bieber.